The present invention relates, in general, to magnetotransistors, and more particularly, to a collector arrangement for magnetotransistors.
Magnetotransistors are magnetic field sensors that are commonly used to detect the presence and orientation of a magnetic field or more particularly a magnetic flux density. Typically, these sensors are semiconductor devices that include an injection region, a conduction region, and a collection region. Charge carriers, i.e., electrons or holes, are injected from the injection region into the conduction region and are subsequently collected in the collection region. An example of such a sensor is a lateral magnetotransistor having an emitter region, a base region, and a collector region, wherein the emitter region serves as the injection region, the base region serves as the conduction region, and the collector region serves as the collection region.
When a magnetic field is applied to the magnetotransistor, it exerts an electromagnetic force on the charge carriers. This force, commonly referred to as a Lorentz force, deflects the charge carriers traveling through the base region thereby creating an imbalance in the number of charge carriers collected by the collector region. In other words, the collector currents become imbalanced. This imbalance may be exploited to determine the strength and orientation of the magnetic flux density.
Two important types of magnetotransistors are two-dimensional (2D) magnetotransistors which detect the x and y directional components, B.sub.x and B.sub.y, respectively, of the magnetic flux density and three-dimensional (3D) magnetotransistors which detect the x, y, and z directional components of the magnetic flux density, B.sub.x, B.sub.y, and B.sub.z, respectively. A drawback of 2D and 3D magnetotransistors is that the noise signals associated with the currents in each collector are uncorrelated and may mask the imbalance in the collector current attributed to the magnetic flux density. Moreover, in 3D magnetotransistors there is a cross-sensitivity between the charge carrier flow in the y-direction and the B.sub.x component of the magnetic flux density, and between the charge carrier flow in the x-direction and B.sub.y component of the magnetic flux density.
Accordingly, it would be advantageous to have a magnetotransistor and a method for making the magnetotransistor that reduces the noise due to the uncorrelated collector currents. It would be of further advantage that the 3D magnetotransistor and the method for making the 3D magnetotransistor eliminate cross-sensitivity between the charge carrier flow in the y-direction and the B.sub.x component and between the charge carrier flow in the x-direction and the B.sub.y component.